\chapter{两角和与差的三角函数}

\input{units/chapter-3-1}
\input{units/xiti-10}

\input{units/chapter-3-2}
\input{units/chapter-3-3}
\input{units/xiti-11}

\input{units/chapter-3-4}
\input{units/xiti-12}

\newpage
\input{units/chapter-3-xiaojie}

\newpage
\nonumsection{复习参考题三}
\input{units/chapter-3-fuxi-A}
\input{units/chapter-3-fuxi-B}
